End-Tidal CO2

Q: Why its called "End-Tidal" CO2?

Answer: It's the point in the respiratory cycle where CO2 is at the highest level (End of the tide)

There are five phases of respiration when it comes to end-tidal Co2 analysis

1. Dead space ventilation
2. Ascending expiratory phase
3. Alveolar Plateau
4. End-tidal CO2
5. Descending inspiratory phase

These five phases are marked in the pic as

A - B: Dead space ventilation

B - C: Ascending expiratory phase

C - D: Alveolar Plateau

D: End-tidal CO2 (highest)

D - E: Descending inspiratory phase

#pulmonary

#procedures

References:

1. Krauss B, Deykin A, Lam A, et al. Capnogram shape in obstructive lung disease. Anesth Analg 2005; 100:884. Copyright © 2005 Lippincott Williams & Wilkins.

2. Zwerneman K. End-tidal carbon dioxide monitoring: a VITAL sign worth watching. Crit Care Nurs Clin North Am. 2006 Jun;18(2):217-25, xi. doi: 10.1016/j.ccell.2006.02.002. PMID: 16728308.

3. Benumof JL. Abnormal end-tidal CO2 waveforms. Can J Anaesth. 2003 Aug-Sep;50(7):754. doi: 10.1007/BF03018728. PMID: 12944461.